KR20210121196A - Curable silicone composition with excellent flame retardancy - Google Patents

Abstract

The present invention relates to a curable silicone composition comprising (A) a polyorganosiloxane polymer, (B) a crosslinked organosilicon compound having at least two silicon-bonded reactive groups, (C) a component (A) and a component (B) a catalyst capable of catalyzing the reaction between; and (D) from 0.001 to 20%, preferably from 0.01 to 16%, more preferably from 0.05 to 12% of bentonite, based on the total weight of the other components in the composition; The bentonite is treated with a treating agent containing at least a quaternary ammonium salt. In addition, the present invention also relates to a method for improving the flame retardancy of a curable silicone composition and a product obtained therefrom.

Description

Curable silicone composition with excellent flame retardancy

The present invention relates to a curable silicone composition having excellent flame retardancy, a method for improving the flame retardancy of the curable silicone composition, and a product obtained from the curable silicone composition of the present invention. The present invention also relates to the use of bentonite for improving the flame retardancy of curable silicone compositions.

Liquid silicone rubber (LSR) is a curable silicone composition, and has already been widely used as a coating composition in various fields such as automobile industry, electronic devices, and medical materials.

For some important products, such as airbags, flame retardancy is strictly required. In order to improve the flame retardancy of the silicone rubber composition, it is common to add various inorganic fillers and organopolysiloxane resins.

US2013099468 uses an organophosphazene compound in a silicone rubber coating on an airbag base fabric to achieve a low burn rate of less than 50 mm/min according to the FMVSS-302 test, the cured coating has low surface tack and high anti-blocking properties indicates

JP3165312 discloses a liquid silicone rubber coating composition for an airbag made of an organopolysiloxane resin, and the silicone rubber of the base fabric having a small amount of coating (17-19 gsm) has excellent combustion rate of less than 50 mm/min. It has flame retardancy.

US5529837A discloses silicone coating compositions containing _{carbon, NiO 2} , FeO, FeO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , CoO ₂ , CeO ₂ or TiO ₂ powders having an average particle size of 2 μM or less. The resulting silicone coating is as thin as 5-20 μm and has flame retardancy with a burning rate of 540 mm/min.

In order to obtain satisfactory flame retardant performance, more inorganic flame retardants should be used than organic halogen-containing-flame retardants, which may cause contamination problems. However, because of the conventional high dosages of inorganic fillers that can ensure approved flame retardancy, silicone coatings containing inorganic filler retardants require less material weight and reduce the amount of VOCs or other harmful contaminants from the coating. It is difficult to achieve low coat weights that are advantageous for a variety of coating applications. Such products are, for example, airbags where both high flame retardancy and low coat weight are important.

Therefore, there is a continuing need to find effective methods for improving the flame retardancy of silicone rubber compositions, and preferably for keeping the coat weight as low as possible.

The inventors of the present application have surprisingly found that the above-mentioned problems can be solved by using a curable silicone composition as defined below. With the composition of the present invention, good flame retardancy (eg as specified in FMVSS-302) can be achieved. In addition, the compositions of the present invention can surprisingly result in a low coat weight of 20 gsm or less, for example 5 to 15 gsm or even about 10 gsm or less without compromising flame retardancy performance. In particular, when coating on woven or polymeric substrates such as polyamide fibers, polyester fibers, woven and non-woven fabrics, or thermoplastic elastomer and polyurethane sheets, the silicone compositions of the present invention can contain up to 70 mm by weight as low as 10 gsm coat weight. Excellent flame retardancy of less than /min and an average of less than 40 mm/min.

In a first aspect, the present invention relates to a curable silicone composition comprising:

(A) a polyorganosiloxane polymer containing a siloxane unit represented by the formula (I-1)

R ¹ _a Z _b SiO _[4-(a+b)]/2 (I-1)

during the meal,

R ¹ is independently selected from the group consisting of hydroxyl, alkoxy, alkenyl, and alkynyl groups,

Z may represent the same or different monovalent hydrocarbon radicals having 1 to 30, preferably 1 to 12 carbon atoms, preferably selected from alkyl and aryl groups,

a is 1, 2 or 3, b is 0, 1 or 2, and the sum of a + b is 1, 2 or 3;

(B) a crosslinked organosilicon compound having at least two silicon-bonded reactive groups;

(C) a catalyst capable of catalyzing the reaction between components (A) and (B); and

(D) from 0.001 to 20%, preferably from 0.01 to 16%, more preferably from 0.05 to 12% of bentonite, based on the total weight of the other components in the composition;

The bentonite is treated with a treating agent containing at least a quaternary ammonium salt.

In a second aspect, the present invention relates to the use of bentonite for improving the flame retardancy of a curable silicone composition, wherein the bentonite is treated with a treating agent containing a quaternary ammonium salt and, based on the total weight of the other components in the composition, from 0.001 to It is characterized in that it is added in an amount of 20%, preferably 0.01 to 16%, more preferably 0.05 to 12%.

In a third aspect, the present invention relates to a method for improving the flame retardancy of a curable silicone composition, wherein bentonite treated with a treating agent containing a quaternary ammonium salt in the composition is 0.001, based on the total weight of other components in the composition. to 20%, preferably 0.01 to 16%, more preferably 0.05 to 12%.

In a fourth aspect, the present invention relates to an article obtained from a curable silicone composition as described above.

curable silicone composition

In the context of this specification, the terms “curable silicone composition”, “silicone rubber composition”, “liquid silicone rubber” and “silicone coating composition” are synonymous and may be used interchangeably. In the automotive industry, airbags are usually manufactured by coating such a composition on a fabric.

The person skilled in the art knows that the so-called curable silicone composition must consist essentially of or comprise an organosilicon compound, a polymer or a resin as the main component of the polymer matrix. In one advantageous embodiment, the polymer matrix of the curable silicone composition comprises at least 50% by weight, preferably at least 65% by weight, more preferably at least 80% by weight, most preferably at least 50% by weight of the total amount of components (A) and (B). contains 90% by weight or 95% by weight or even 100% by weight.

Component (A)

Component (A) is a polyorganosiloxane polymer containing siloxane units represented by formula (I-1)

R ¹ _a Z _b SiO _[4-(a+b)]/2 (I-1)

during the meal,

R ¹ is independently selected from the group consisting of hydroxyl, alkoxy, alkenyl, and alkynyl groups,

Z may represent the same or different monovalent non-reactive hydrocarbon radicals having 1 to 30, preferably 1 to 12 carbon atoms, preferably selected from alkyl and aryl groups,

a is 1, 2 or 3, b is 0, 1 or 2, and the sum of a + b is 1, 2 or 3.

In addition, the polyorganosiloxane polymer optionally contains at least one siloxane unit having the formula (I-2):

(I-2)

(I-2)

During the ceremony:

- c = 0, 1, 2 or 3,

- Z ¹ may represent the same or different monovalent non-reactive hydrocarbon radicals having 1 to 30, preferably 1 to 12 carbon atoms, preferably selected from alkyl and aryl groups.

Advantageously, the polyorganosiloxane polymer may consist essentially of siloxane units of the formulas (I-1) and (I-2). It may have a viscosity of at least 50 mPa.s, preferably less than 200,000 mPa.s. Herein, all viscosity data relate to kinematic viscosity values and, unless otherwise specified, can be measured in a known manner at 20° C. using, for example, a Brookfield instrument.

The polyorganosiloxane polymer may be of a linear, branched, or cyclic structure. One of ordinary skill in the art is skilled in the art that in the case of a linear or branched structure the polyorganosiloxane polymer may contain -R' or -SiR' ₃ groups, wherein R' independently of each other are hydroxyl or hydrocarbonyl groups such as alkyl, alkoxy, alkenyl, alkyl. represents nyl or aryl).

In the context of the present invention, alkyl and alkoxy groups may advantageously have 1 to 18, more preferably 1 to 12 and most preferably 1 to 8 carbon atoms, and thus for example methyl, ethyl, propyl, methoxy and ethoxy groups. Alkenyl and alkynyl groups may preferably have 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms, and thus include, for example, vinyl, propenyl and ethynyl groups. Aryl groups may preferably have 6 to 20, more preferably 6 to 12 carbon atoms and thus include, for example, phenyl, tolyl, xylyl or naphthyl groups.

In one exemplary embodiment, Z or Z ¹ is selected from a C ₁ -C ₈ alkyl group and/or a C ₆ -C ₂₀ aryl group.

Examples of the siloxane unit of formula (I-1) may include vinyl dimethylsiloxy, vinylphenylmethylsiloxy, vinyl methylsiloxy and vinyl siloxane units.

Examples of siloxane units of formula (I-2) are SiO _4/2 units, dimethyl siloxy, methyl phenyl siloxy, diphenyl siloxy, methyl siloxy and phenyl siloxy groups.

Examples of polyorganosiloxane polymers include linear or cyclic compounds such as dimethylpolysiloxane (containing dimethylvinylsilyl end groups), (methylvinyl) (dimethyl) polysiloxane copolymers (containing trimethylsilyl end groups), (methyl vinyl) (dimethyl) polysiloxane copolymers (containing dimethylvinylsilyl end groups) and cyclic methyl vinyl polysiloxanes.

In one preferred embodiment of component (A), the polyorganosiloxane polymer may comprise an alkenyl polysiloxane resin A' comprising or consisting of:

at least 2 selected from the group consisting of a siloxane unit M of the formula R ₃ SiO _1/2 , a siloxane unit D of the _{formula R 2} SiO _2/2 , a siloxane unit T of the _{formula RSiO 3/2 and a siloxane unit Q of the formula SiO 4/2} 2 different siloxane units, wherein R represents a monovalent hydrocarbon group having 1 to 20 carbon atoms,

provided that at least one of these siloxane units is a siloxane unit T or Q, and at least one of the siloxane units M, D and T comprises an alkenyl group.

Advantageously, the polysiloxane resin A' has a weight average molecular weight in the range from 200 to 100,000, preferably from 200 to 50,000, more preferably from 500 to 30,000. In this case, the weight average molecular weight can be obtained by gel permeation chromatography using polystyrene as a standard.

Advantageously, when all or substantially all alkenyl groups in the polyorganosiloxane polymer or preferably polysiloxane resin A' are bonded to siloxane units M (M ^Vi units) or siloxane units D (D ^Vi units), the present invention The silicone composition of the present invention can be cured at room temperature or at a higher temperature more rapidly than with alkenyl groups bonded in other ways.

The above-mentioned are only some examples of polysiloxane resin A'. It will be apparent to those skilled in the art that other resins composed of the units M, T, D and Q are also suitable for use as polysiloxane resins.

In one embodiment, the amount of polysiloxane resin A' may range from 0 to 50% by weight, more preferably from 1 to 40% by weight, in particular from 5 to 35% by weight, based on the total weight of the composition.

In the context of the present invention, when referring to a composition or component, in particular a polysiloxane resin or component (A) and (B), the term "consisting/comprising (substantially)... is meant to comprise more than 50% by weight, for example at least 60% by weight, at least 70% by weight, or at least 80% by weight, or even 100% by weight of the listed substances, based on the total weight of the components.

Component (B)

Component (B) is a crosslinked organosilicon compound having at least 2 or even 3 silicon-bonded reactive groups per molecule, which is based on component (A) described above and in particular on the basis of a curing mechanism as well known to the person skilled in the art. ^{with reactive groups R 1} such as alkenyl or hydroxyl groups of component (A), respectively. The cross-linked organosilicon compound may be a monomer, oligomer or polymer. In one embodiment, they preferably have a viscosity of less than or equal to 1000 mPa.s at 25° C., more preferably between 2 and 500 mPa.s at 25° C.

In one possible embodiment, suitable crosslinking organosilicon compounds are polyfunctional silane compounds capable of initiating a condensation reaction, generally of the formula R _4-n Si-Y _n , wherein n is 3 or 4 and R is a non-reactive hydrocarbonyl group such as alkyl or aryl, and Y is a hydrolyzable functional group. Depending on the various crosslinking mechanisms with the polysiloxane polymer, the group Y can be a carbonyloxy (-OCO-), an oxime (-ON=C<), an ether (-O-), an amine, an amide (>N-CO-), It may contain alkenyloxy and/or aminooxyl (-ON<) groups. Thus, the group Y is alkoxy (-OR"'), -OCOR"', -ON=CR"' ₂ , -NHR"', -NR"'COR"', -OC(R"')=CH ₂ and -ONR"' ₂ wherein R"' represents an alkyl or aryl having 1 to 30 carbon atoms, preferably a non-reactive hydrocarbonyl group such as methyl, ethyl, propyl) Methods for preparing these crosslinked organosilicon compounds are well known to those skilled in the art or readily available.

In another preferred embodiment, the crosslinking organosilicon compound has the formula R ⁴ _a′ R ⁵ _b′ SiO _{4-a′-b′/2} , wherein R ⁴ is alkyl having from 1 to about 18 carbon atoms, and is selected from the group consisting of aryl groups, R ⁵ is a reactive group selected from the group consisting of hydrogen, hydroxy, and alkoxy, a' has a value of 0 or 1, b' has a value of 2-3, a the sum of '+b' is the value of 2 or 3), a monomer, homopolymer, copolymer or mixture thereof.

As discussed above, the reactive groups bound to Si atoms in component (B) are selected according to the selection of functional groups in component (A) and the various curing mechanisms. For example, for a preferred addition curing reaction, the crosslinking organosilicon compound is a hydrogen-containing polysiloxane containing at least two, preferably three or more Si—H groups bonded to the same or different silicon atom(s) per molecule. may be reacted and crosslinked with the alkenyl group in component (A) according to a hydrosilylation mechanism to form a cured product.

In one preferred embodiment of the addition curing reaction, the hydrogen-containing polysiloxane comprises:

(i) at least two siloxane units and preferably at least three siloxane units having the formula:

(II-1)

(II-1)

During the ceremony:

- d = 1 or 2 or 3, e = 0, 1 or 2, d+e = 1, 2 or 3,

- Z ³ is the same or different, preferably selected from C ₁ -C ₈ alkyl and C ₆ -C ₂₀ aryl groups, monovalent hydrocarbon radicals having 1 to 30, preferably 1 to 12 carbon atoms may represent, and

(ii) optionally at least one siloxane unit having the formula:

(II-2)

(II-2)

During the ceremony:

- f = 0, 1, 2 or 3,

- Z ³ is the same or different and may have the same meaning as given above.

In a preferred embodiment, Z ³ may be selected from the group consisting of methyl, ethyl, propyl, 3,3,3-trifluoropropyl, phenyl, xylyl and tolyl and the like.

The hydrogen-containing polysiloxane has a kinematic viscosity of at least 10 mPa.s, preferably between 20 and 1000 mPa.s.

The hydrogen-containing polysiloxane may consist substantially of units of formula (II-1) and any units of formula (II-2). The hydrogen-containing polysiloxane may be of a linear, branched, or cyclic structure. Likewise, the person skilled in the art also knows that in the case of a linear or branched structure component (B), preferably a hydrogen-containing polysiloxane, has a -R" or -SiR" ₃ group, wherein R" independently of one another has the meaning given for the ^{Z 3 group.} or represents H).

Examples of units of formula (II-1) include H(CH ₃ ) ₂ SiO _1/2 , HCH ₃ SiO _2/2 and H(C ₆ H ₅ )SiO _2/2 .

Examples of units of formula (II-2) may be the same as those given above for units of formula (I-2).

Examples of hydrogen-containing polysiloxanes include linear, branched or cyclic compounds such as dimethylpolysiloxane (containing hydrogenated dimethylsilyl end groups), copolymers having (dimethyl) (hydromethyl) polysiloxane units (including trimethylsilyl end groups) ), copolymers having (dimethyl) (hydromethyl) polysiloxane units (including hydrogenated dimethylsilyl end groups), hydrogenated methyl polysiloxanes having trimethylsilyl end groups, and cyclic hydrogenated methyl polysiloxanes.

In some cases, the hydrogen-containing polysiloxane may be a mixture of a dimethylpolysiloxane containing hydrogenated dimethylsilyl end groups and an organopolysiloxane containing at least three hydrosilyl groups.

^{When a reactive group such as R 1} of component (A) is a hydroxyl or alkoxy group, it is preferable that the reactive group in the cross-linked organosilicon compound is an alkoxy group or a hydroxyl group, respectively, which allows a condensation reaction to occur between the two components . When the reactive group of component (A) is a hydroxyl or alkenyl group, the reactive group in the crosslinking organosilicon compound may be a hydrogen atom, allowing a condensation or addition reaction between the two components.

Component B is used in an amount conventionally used to prepare a curable liquid silicone rubber composition. The amount used will depend on the particular crosslinking mechanism of the selected reactive group and the properties desired. In an exemplary embodiment, for the condensation-cured composition, crosslinking component B is present in an amount of about 0.1 to 15 parts by weight per 100 parts by weight of component A.

In order to obtain a high quality cured product using addition curing, the molar ratio of the total silicon-bonded hydrogen of component B to the silicon-bonded alkenyl groups of component A is preferably in the range of 1:2 to 15:1. Even more preferably, component B is added in a concentration sufficient to provide that the molar ratio of silicon-bonded hydrogen to silicon-bonded alkenyl provided by component A ranges from about 1:1 to 3:1. .

Component (C)

Component (C) is a catalyst capable of catalyzing or promoting the reaction between components (A) and (B). Depending on the type of crosslinking reaction of the silicone rubber composition, ie condensation or addition reaction, the skilled person selects a specific suitable compound for component (C).

In one embodiment of a silicone coating composition that is cured by a condensation reaction, the catalyst may be any known condensation catalyst, such as a catalyst based on tin or titanium. Useful organotin compounds are those having a valency of tin of +2 or +4. These tin compounds are known in the art to catalyze the reaction between substituted alkoxy groups on silicon and hydroxyl groups substituted on silicon. Typical tin compounds useful as condensation catalysts include tin salts of carboxylic acids such as tin stearate, tin oleate, tin naphthanate, tin hexoate, tin succinate, tin caprylate, and tin octoate; and tin salts of carboxylic acids, such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin diformate, and dibutyltin dineodecanoate, as well as Included are partially hydrolyzed products of the above. For the purposes of the present invention, dibutyltin dilaurate, dimethyltindineodecanoate, and tin octoate are preferred catalysts.

In one embodiment of the silicone coating composition that is cured by addition reaction, suitable addition catalysts include catalysts based on platinum group metals such as rhodium, ruthenium, palladium, osmium, iridium or platinum containing catalysts. Platinum-based catalysts are particularly preferred and may take any known form ranging from platinum deposited on a carrier such as powdered charcoal to platinum chloride, salts of platinum, chloroplatinic acid, and encapsulated forms thereof. Preferred forms of the platinum catalyst include complexes of platinum halides with unsaturated compounds such as chloroplatinic acid, platinum acetylacetonate, ethylene, propylene, organovinylsiloxane and styrene; hexamethyldiplatinum, PtCl ₂ , PtCl ₃ , PtCl ₄ and Pt(CN) ₃ . Alternatively, the platinum group catalyst is a platinum catalyst. Suitable forms of platinum catalyst include chloroplatinic acid, 1,3-diethenyl-1,1,2,2-tetramethyldisiloxane platinum complex, platinum halide or complex of chloroplatinic acid with divinyldisiloxane and chloroplatinic acid, divinyldisiloxane complexes formed by the reaction of vinyltetramethyldisiloxane and tetramethyldisiloxane, but are not limited thereto.

Component (C) is used in an amount sufficient to crosslink the silicone rubber composition of the present invention within a desired time which can be typically determined by routine experimentation. In general, the condensation catalyst may be added at a level of about 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, for each 100 parts by weight of component (A). Also, an effective amount of an addition catalyst, such as a platinum-based catalyst, is, for example, from about 0.1 to 1000 parts by weight of metal per million parts (eg, platinum), based on the total weight of the composition, preferably from 2 to 100 ppm, more Preferably, it may be 5 to 50 ppm.

Component (D)

Component (D) is a bentonite treated with a treating agent containing at least a quaternary ammonium salt. Preferably, it is a nanoscale platelet filler bentonite compound. Nanoscale platelet fillers may be in the form of nanocomposites, which are dispersions of fillers such as bentonite materials in polymers or resins. The bentonite material is surface treated with a treatment agent containing a quaternary ammonium salt to be retained on its surface. Quaternary ammonium salts contain a carbon chain of 6 to 30, preferably 10 to 18 carbon atoms.

In one embodiment, suitable quaternary ammonium salts include alkyl quaternary ammonium salts containing an alkyl carbon chain from _{C 6} -C ₃₀ , preferably C ₁₀ -C _{18 .} In addition to the quaternary ammonium salts, the treating agents include functional organosilane compounds containing vinyl, amino, alkyl, methacryloxy and epoxy groups; organic titanate coupling agents; octadecanoic acid; and at least one adjuvant selected from other compounds containing a functional group capable of causing or promoting the same treatment effect. Preferably, the therapeutic agent contains or consists of at least 50%, more preferably at least 60% or at least 70% or 90% by weight of a quaternary ammonium salt and optionally said adjuvant. In one advantageous embodiment, the bentonite is treated with a quaternary ammonium salt in an amount of more than 15%, preferably more than 30%, calculated by ammonium ions and based on the total weight of bentonite treated.

Also preferably, the bentonite material is halogen-free. Commercial products of such bentonite compounds include, for example, Garamite® 1958 or Garamite® 1210. Also preferably, no halogen or halogen-containing compounds are contained in the composition.

Surprisingly, it has been found that bentonite compounds surface-treated with at least a quaternary ammonium salt are well compatible with the silicone matrix and exhibit good flame retardant performance while keeping the coat weight of the silicone composition low below 10 gsm.

In one embodiment, the treated bentonite compound preferably has a particle size D50 = 1 to 50 μm, such as 5 to 30 μm.

The bentonite compound is added in an amount of 0.001 to 20%, preferably 0.01 to 16%, more preferably 0.05 to 12%, such as 0.1% or 0.15% to about 11%, based on the total weight of the other components in the composition. do. It has been shown that even a small amount of bentonite compound improves flame retardancy surprisingly. However, when the amount exceeds 20%, low coat weight properties or even processability may also deteriorate.

any other ingredients

In addition to the above-mentioned components (A) to (D), the curable silicone composition according to the present invention may optionally contain further components to adjust the overall properties of the composition as desired.

One example of such an additional ingredient is an adhesion promoter. In one embodiment of the present invention, the adhesion promoter may be at least one selected from epoxy silane, alkoxy silane, acyloxy silane, aryloxy silane or oligomers thereof. These are 3-glycidoxypropyl trimethoxy silane, octyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, gamma-methacryloxy-propyltrimethoxysilane, beta-(3,4-epoxy) Cyclohexyl)-ethyltrimethoxysilane beta-(3,4-epoxycyclohexyl)-ethyltriethoxysilane and bis(trimethoxysilyl propyl) fumarate, alkoxy or aryloxy silicones such as trimethoxysilyl functional groups including, but not limited to, modified silicones. In addition, they are also silanols, oligosiloxanes containing at least one alkoxysilyl function, polysiloxanes containing alkoxysilyl functions, at least one oligomeric siloxane containing hydroxyl functions, polysiloxanes containing at least one aryloxysilyl function, polysiloxanes containing at least one aryloxysilyl function, cyclosiloxanes containing alkoxy silyl functionality, cyclosiloxanes containing one or more hydroxyl groups, tetra-alkoxy silanes, vinyltrimethoxysilanes, and mixtures thereof, and combinations thereof.

The amount of the adhesion promoter may be 0.01 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of component (A).

Examples of components that may further be contained in the composition include pigments, colorants, or other fillers such as silica, calcium carbonate, quartz, wollastonite, cerium oxide, Al(OH) ₃ , Fe ₂ O ₃ , Al ₂ O ₃ , Mica, talc, MgO, Mg(OH) ₃ , TiO ₂ includes. However, these fillers are preferably used in an amount of less than 30% by weight, preferably less than 10% by weight, or more preferably less than 5%, or even 0%, since large amounts of these fillers are used in any of the flame retardant properties. It will not contribute to further improvement of In a preferred embodiment, the composition contains silica and/or calcium carbonate in an amount of preferably 1-25% by weight, more preferably 5-20% by weight, based on the total weight of the composition.

In the method for improving the flame retardancy of a curable silicone composition, the method of the present invention comprises, in the composition, bentonite treated with a treating agent containing at least a quaternary ammonium salt, based on the total weight of other components in the composition, from 0.001 to 20%. , preferably in an amount of 0.01 to 16%, more preferably 0.05 to 12% of bentonite.

The mixing order of the individual components of the silicone composition of the present invention is not strictly limited. In one embodiment according to the method of the invention, the premix of components (A), (B) and optionally component (C) can be initially formed under sufficient stirring, for example at ambient temperature, followed by component ( D) Treated bentonite is added to the premix.

After the preparation of the silicone composition of the present invention, the curing reaction is initiated under different reaction conditions according to the crosslinking mechanism.

In a final aspect of the present specification, the present invention relates to an article obtained from a curable silicone composition as described above. In an exemplary embodiment, the article is coated with the curable silicone composition of the present invention on a substrate in any conventional manner, such as dip coating, roll coating and brush coating, etc., followed by heating or without heating the composition under suitable conditions known to those skilled in the art. It can be obtained by curing In an exemplary embodiment, curing may be carried out at a temperature of 120 to 220° C. for up to 10 minutes or preferably 5 minutes, for example at a temperature of 150 to 180° C. for 45 to 120 seconds.

In a preferred embodiment, a suitable substrate onto which the curable silicone composition of the present invention is coated is a fabric comprising, for example, a fabric, a polymer film, a thermoplastic elastomer, a metal, a glass, such as a fiberglass or a ceramic material, preferably a woven or non-woven fabric. , or polymeric films or sheets such as polypropylene, polyethylene, polyamide, poly(ethylene) terephthalate, polyurethane, polyester, and compositions or mixtures thereof. In a preferred embodiment, such an article may be an airbag.

Example

The first part of the coated fabric flame test

Test Sample Preparation:

The silicone liquid coating composition is knife coated on the fabric and cured at 160° C. for 2 minutes.

Fabric: Polyamide 66, 470dtex, 51*51(cm)

Coat weighing: weighing the blank before coating (W1), weighing the coated fabric after curing (W2) and measuring the coated area S. Calculate the weight according to the formula:

CW= (W2-W1)/S, in grams per square meter

Test Equipment:

Test standard: FMVSS-302

Test conditions: no wire, uncoated side facing fire;

Raw material:

Example 1 (Comparative Example 1)

75.53 parts of component A1 with 14.655 parts of precipitated calcium carbonate, 5.45 parts of component B1 and 0.02 parts of 1-ethynyl-1-cyclohexanol were loaded and mixed in a 100 g speed mixer cup under 2000 rpm for 30 seconds. Then, 0.75 parts of vinyltrimethoxysilane and 1.45 parts of (3-glycidyloxypropyl)trimethoxysilane as accelerators are added to a speed mixer and mixed at 2000 rpm for 30 seconds, after which 2.1 parts of titanium tetrabutanolate and 0.03 parts of component C1 were added and further mixed under 2000 rpm for 30 seconds. The prepared mixture of Example 1 was tested for flame retardancy and used as a premix for Examples 2-6.

Examples 2-8

Samples of examples 2-8 were prepared by adding the respective fillers, namely Garamite 1958, CP-250, CP-27, wollastonite, aluminum hydroxide and iron oxide in the respective amounts specified in Table 1, to the premix according to Example 1, followed by It was prepared by mixing in a speed mixer at 2000 rpm for 30 seconds. Compositions and test results are presented in Table 1.

Comparative formulation (comparative)

75.53 parts of component A1 with 14.655 parts of untreated bentonite, 5.45 parts of component B1 and 0.02 parts of 1-ethynyl-1-cyclohexanol were loaded and mixed in a 100 g speed mixer cup under 2000 rpm for 30 seconds. Then, 0.75 parts of vinyltrimethoxysilane and 1.45 parts of (3-glycidyloxypropyl)trimethoxysilane as accelerators are added to a speed mixer and mixed at 2000 rpm for 30 seconds, after which 2.1 parts of titanium tetrabutanolate and 0.03 parts of component C1 were added and further mixed under 2000 rpm for 30 seconds.

Table 1

Test result:

Examples 4-6 cannot achieve a low coat weight of 10 gsm under the same coating conditions.

The above experiments showed that average burn rates of less than 40 mm/min can be achieved with only 3% bentonite, and coat weights as low as about 10 gsm can be achieved by knife coating. For other fillers, coat weights do not reach levels below 15 gsm, and even at much higher doses, it is still difficult to achieve average burn rates of less than 40 mm/min.

Test Sample Preparation:

The silicone liquid coating composition is knife coated on the fabric and cured at 160° C. for 2 minutes.

Fabric: Polyamide 66, 470dtex, 46*46 (cm)

Coat weighing: weighing the blank before coating (W1), weighing the coated fabric after curing (W2) and measuring the coated area S. Calculate the weight according to the formula:

CW= (W2-W1)/S, in grams per square meter

Test Equipment:

Test standard: FMVSS-302

Test conditions: no wire, uncoated side facing fire;

Table 2

Test result:

Examples 9, 10 and 12 were also prepared based on the premix as described above with the addition of various fillers as listed in Table 2. All of them showed better flame retardant performance in the fabric compared to Example 1, and a 0.25% dose of treated bentonite can improve the performance by 40%.

Part 2 for Cured Silicone Elastomer Flame Test

Test Sample Preparation:

After degassing for 2 to 10 minutes, the mixed liquid silicone is poured into a 2 mm thick Teflon-treated metal mold and then cured in an oven at 150° C. for 30 minutes. The cured slabs were cut into 2 cm wide and 15 cm long pieces, and they were placed under 23±2° C., 50±5%RH for 48 hours.

Test conditions: Each specimen is supported so that its lower end is 10 mm above the Bunsen burner tube. Then, hang the specimen. A blue 20 mm high flame is applied to the center of the lower edge of the specimen for 10 s and then removed. For each formulation, 5 specimens are tested, and the individual digestion time for each specimen is recorded. t1 is reported as an average of 5 digestion times.

Example 13 (Comparative Example 2):

95.27 parts of component A2, 3.12 parts of component B2, 1.45 parts of component B3 and 0.155 parts of methylvinylcyclosiloxane are loaded and mixed in a 100 g speed mixer cup under 2000 rpm for 30 seconds, after which 0.0182 parts of component C1 are added, 2000 Mix further for 30 seconds at rpm. The prepared mixture of Example 13 was tested for flame retardancy and used as a premix for Examples 14-15.

Examples 14-15

Samples of Examples 14-15 were prepared by adding Garamite 1958 to the premix according to Example 13 in the various amounts specified in Table 2, followed by mixing in a speed mixer at 2000 rpm for 30 seconds. Compositions and test results are presented in Table 3.

Table 3

Test result:

The above experiments showed that with only 3 parts of bentonite an average t1 of less than 50 seconds can be achieved.

Part 3 for Cured Silicone Elastomer Flame Test

Test Sample Preparation:

After degassing for 2-10 minutes, the mixed liquid silicone is poured into a 2 mm thick Teflon-treated metal mold at room temperature, followed by curing in an oven for 24 hours. The cured slabs were cut into 2 cm wide and 15 cm long pieces, and they were placed under 23±2° C., 50±5%RH for 48 hours.

Test conditions: Each specimen is supported so that its lower end is 10 mm above the Bunsen burner tube. hang the psalms Then, a blue 20 mm high flame is applied to the center of the lower edge of the specimen for 10 s and removed. Record burn time and burn distance.

Example 16 (Comparative Example 3)

58.37 parts of component A3 having 24.991 parts of component B4, 12.65 parts of untreated quartz filler and 0.285 parts of hydroxyl terminated polydimethylsiloxane oil having a viscosity of 45 mpa.s are loaded, and in a 100 g speed mixer cup under 2000 rpm for 30 seconds Mixed, followed by addition of 3.58 parts of component C2. The prepared mixture of Example 16 was tested for flame retardancy and used as a premix for Example 17.

Example 17

A sample of Example 17 was prepared by adding 100 parts of the premix of Example 16 and 3 parts of Garamite 1958 to a 100 g speed mixer cup and then mixing in a speed mixer at 2000 rpm for 30 seconds. Compositions and test results are presented in Table 3.

Table 4

Test result:

Only 3 parts of treated bentonite can occupy half the burn distance.

Claims (18)

A curable silicone composition comprising:
(A) a polyorganosiloxane polymer containing a siloxane unit represented by the formula (I-1)
R ¹ _a Z _b SiO _[4-(a+b)]/2 (I-1)
during the meal,
R ¹ is independently selected from the group consisting of hydroxyl, alkoxy, alkenyl, and alkynyl groups,
Z may represent the same or different monovalent non-reactive hydrocarbon radicals having 1 to 30, preferably 1 to 12 carbon atoms, preferably selected from alkyl and aryl groups,
a is 1, 2 or 3, b is 0, 1 or 2, and the sum of a + b is 1, 2 or 3;
(B) a crosslinked organosilicon compound having at least two silicon-bonded reactive groups;
(C) a catalyst capable of catalyzing the reaction between components (A) and (B); and
(D) from 0.001 to 20%, preferably from 0.01 to 16%, more preferably from 0.05 to 12% of bentonite, based on the total weight of the other components in the composition;
Bentonite is treated with a treatment containing at least a quaternary ammonium salt. Curability according to claim 1, characterized in that the bentonite is treated with a quaternary ammonium salt in an amount of more than 15%, preferably more than 30%, calculated by ammonium ions and based on the total weight of the treated bentonite. silicone composition. The curable silicone composition according to claim 1, wherein the polyorganosiloxane polymer contains at least one siloxane unit having the formula (I-2):

(I-2)
During the ceremony:
- c = 0, 1, 2 or 3,
- Z ¹ may represent the same or different monovalent non-reactive hydrocarbon radicals having 1 to 30, preferably 1 to 12 carbon atoms, preferably selected from alkyl and aryl groups. 4. Curable silicone composition according to any one of claims 1 to 3, characterized in that Z or Z ¹ is selected from C ₁ -C ₈ alkyl groups and/or C ₆ -C _{20 aryl groups.} 5. The polyorganosiloxane polymer according to any one of claims 1 to 4, wherein the polyorganosiloxane polymer is a siloxane unit M of the _{formula R 3} SiO _1/2 , a siloxane unit D of the _{formula R 2} SiO _{2/2 , a formula RSiO 3/2} at least two different siloxane units selected from the group consisting of a siloxane unit T of and _{a siloxane unit Q of the formula SiO 4/2} , wherein R represents a monovalent hydrocarbon group having 1 to 20 carbon atoms
(provided that at least one of these siloxane units is a siloxane unit T or Q, and at least one of the siloxane units M, D and T comprises an alkenyl group)
A curable silicone composition comprising an alkenyl polysiloxane resin A' containing 6. The cross-linked organosilicon compound according to any one of claims 1 to 5, wherein the cross-linked organosilicon compound has the formula R ⁴ _a' R ⁵ _b' SiO _4-a'-b'/2 , wherein R ⁴ is from 1 to about 18 selected from the group consisting of alkyl, aryl, and halogenated alkyl groups having carbon atoms, R ⁵ is a reactive group selected from the group consisting of hydrogen, hydroxy, and alkoxy, a' has a value of 0 or 1, b ' has a value of 2 to 3, and the sum of a'+b' is a value of 2 or 3) . 7. Hydrogen according to any one of the preceding claims, wherein the crosslinked organosilicon compound contains at least two, preferably three or more Si—H groups bonded to the same or different silicon atom(s) per molecule. - A curable silicone composition comprising a polysiloxane containing. 8. The curable silicone composition of claim 7, wherein the hydrogen-containing polysiloxane comprises:
(i) at least two siloxyl units, preferably at least 3 siloxyl units having the formula:

(II-1)
During the ceremony:
- d = 1 or 2 or 3, e = 0, 1 or 2, d+e = 1, 2 or 3,
- Z ³ is the same or different, preferably selected from C ₁ -C ₈ alkyl and C ₆ -C ₂₀ aryl groups, monovalent hydrocarbon radicals having 1 to 30, preferably 1 to 12 carbon atoms may represent, and
(ii) optionally at least one siloxane unit having the formula:

(II-2)
During the ceremony:
- f = 0, 1, 2 or 3,
- Z ³ is the same or different and may have the same meaning as given above. 9. Curable silicone composition according to any one of claims 1 to 8, characterized in that the quaternary ammonium salt contains a carbon chain of 6 to 30, preferably 10 to 18 carbon atoms. 10. The quaternary ammonium salt according to any one of claims 1 to 9, wherein said quaternary ammonium salt comprises an alkyl quaternary ammonium salt containing an alkyl carbon chain from _{C 6} -C ₃₀ , preferably C ₁₀ -C _{18 .} Curable silicone composition, characterized in that. 11. The method according to any one of claims 1 to 10, wherein the treating agent is a functional organosilane compound containing vinyl, amino, alkyl, methacryloxy and epoxy groups; organic titanate coupling agents; octadecanoic acid; and at least one selected from other compounds containing a functional group capable of causing the same treatment effect. 12. The curable silicone composition of any one of claims 1-11, wherein the composition further comprises an adhesion promoter. 13. The curable silicone composition of claim 12, wherein the adhesion promoter is an organosilicon compound having at least one alkenyl group and at least one epoxy and/or trialkoxysilyl group bonded to the same or different silicon atoms. 14. The method according to any one of claims 1 to 13, wherein the total amount of components (A) and (B), based on the polymer matrix of the composition, is greater than 50% by weight, preferably greater than 65% by weight, more preferably Curable silicone composition, characterized in that it is greater than 80% by weight, particularly preferably greater than 90% by weight. 15. The composition according to any one of claims 1 to 14, wherein the composition preferably contains silica and/or carbonic acid in an amount of 1-25% by weight, more preferably 5-20% by weight, based on the total weight of the composition. Curable silicone composition containing calcium. The use of bentonite for improving the flame retardancy of a curable silicone composition as defined in claim 1, wherein the bentonite is treated with a treatment agent containing a quaternary ammonium salt, based on the total weight of the other components in the composition, from 0.001 to 20% , preferably in an amount of 0.01 to 16%, more preferably 0.05 to 12%. A method for improving flame retardancy of a curable silicone composition as defined in claim 1, wherein the bentonite treated with a treating agent containing a quaternary ammonium salt in the composition is added, based on the total weight of other components in the composition, by 0.001 to 20%; A method for improving flame retardancy comprising adding preferably in an amount of 0.01 to 16%, more preferably 0.05 to 12%. A product obtained by curing the curable silicone composition as defined in any one of claims 1 to 15, in particular an airbag.